This invention relates to the field of turbine generators, and more particularly, this invention relates to a clamping apparatus and method for clamping of stator coil windings within a turbine generator.
Turbine generators for producing electric power are well known and typically include an end winding portion that includes a stator core having several slots that receive and support conductors. The end windings may not be adequately supported within the core slots during operation of the generator and are often subject to severe vibrations and stresses, which may cause adverse structural deformations. Structural deformation may also arise from electromagnetic forces which occur during abnormal short-circuit or fault conditions.
Several techniques have been developed in an attempt to prevent the end windings from undergoing negative structural deformations, such as that disclosed in U.S. Pat. No. 4,563,607 to Cooper et al. for a radial clamp assembly for dynamoelectric machine stator coil end turns. Top and bottom coils disposed within slots stator iron core are supported with a radial clamp, braces, brackets, rings and stain blocks.
The radial clamp is typically positioned in the mid-involute region between the axial extreme of the end winding and the core.
The support blocks are located radially above and below a respective pair of end turns so that one support block bears against two parallel bottom coils and the other support block bears against two parallel top coils.
Upper and lower pins are disposed across the support block transverse to the orientation direction of the coils. A tensioned banding loop is disposed continuously around the pins on each side of the coils so that the banding loop bears against the pins which, in turn, bear against their adjacent support blocks and coils.
With the banding loop in position, the pins are rotated to twist the banding loop for taking in excess slack, thereby tightening the banding loop between the coils. Resin dispersed within the banding loop is then cured on site, typically by hot air flowing over the banding loop. The curing process requires additional time and expense to install. Typically, band curing extends work schedules and consequently adds to the overall cost of the turbine generator.
U.S. Pat. No. 6,054,792, assigned to the present assignee and hereby incorporated by reference in its entirety, provides a more economical means of installing and maintaining a turbine generator and reduces the number of components that must be accounted for during the installation of the radial clamps.
In the ""792 disclosure, a clamping apparatus includes a retaining platform for extending across a pair of coil windings positioned in a spaced relation. The retaining platform has a bore extending therethrough. A connecting insert member is slidably carried within the bore of the retaining platform. The connecting insert member has a through-hole and means for admitting a rod into the through-hole. The rod passes through the through-hole of the connecting insert member and includes a bulbous shaped end dimensioned for passing through the bore of the retaining platform while the through-hole of the connecting insert member prevents passage of the bulbous shaped end therethrough. Thus, tension in the rod biases the platform against the coil windings.
In one preferred embodiment, the connecting insert member comprises separable mating segments as the means for admitting a rod into the through-hole. The through-hole of the connecting insert member includes a first dimension that permits passage of the bulbous end therein, and a second dimension that prevents passage of the bulbous end therethrough. In one embodiment, the connecting insert member has a tapered cross-section for slidably securing the member within the bore of the retaining platform.
Although the ""792 patent discloses an advantageous mechanism for clamping turbine generator coil windings, it would be desirable if a clamp design were even quicker to install and allowed a more simple structure.
The present invention is advantageous and now provides a clamping apparatus useful for clamping opposing pairs of stator coil windings of a turbine generator in a quick and efficient manner. A retaining platform is positioned adjacent one side and across a pair of coil windings having a space therebetween and having a bore extending therethrough that is aligned with the space between the pair of coil windings. A connecting insert member is carried within the bore of the retaining platform and has a threaded through-hole aligned with the space between the pair of coil windings. A threaded rod extends through the space between the pair of coil windings and through the threaded through-hole of the connecting insert member. This threaded rod mates with the threaded through-hole such that the tension created in the threaded rod during tightening biases the retaining platform against the pair of coil windings.
In one aspect of the present invention, the threaded rod is used with shims for increasing or decreasing tension within the threaded rod and increasing or decreasing biasing of the retaining platform against the pair of coil windings. The threaded rod is preferably formed from a material wherein the compression of the threads is increased with increased tension. An example of such a material is resin treated fiberglass. The connecting insert member in one aspect of the invention has a tapered cross-section adjustably secured within the bore of the retaining platform.
In yet another aspect of the present invention, a support block is positioned between the retaining platform and across the pair of coil windings and has an aperture therethrough for aligning with the space between the pair of coil windings and the bore of the retaining platform. The connecting insert member includes separable mating segments that include mating arcuate portions forming the through-hole. The pair of coil windings are positioned parallel and in a spaced relation, thus having a space therebetween when tension is applied.
In yet another aspect of the present invention, a first retaining platform is positioned adjacent one side and across a first pair of coil windings having a space therebetween. This first retaining platform has a bore extending therethrough that is aligned with the space between the first pair of coil windings. A second retaining platform is positioned adjacent one side and across a second pair of coil windings having a space therebetween. The second retaining platform has a bore extending therethrough for aligning with the space of the second pair of coil windings. The first and second pair of coil windings are sandwiched between first and second retaining platforms.
First and second connecting insert members are each respectively carried within each bore of the retaining platform and each of the connecting insert portions has a threaded through-hole. A threaded rod passes through each of the spaces of the first and second pairs of coil windings and passes through the through-holes of the connecting insert members. The threaded rod mates with each threaded through-hole such that tension in the threaded rod biases the retaining platform against the pairs of coil windings.
A method is disclosed for clamping opposing pairs of stator coil windings of a turbine generator. A threaded rod is inserted through a space formed between a pair of coil windings and through a threaded through-hole of a connecting insert member that is received within a bore of a retaining platform positioned adjacent one side and across the pair of coil windings. This threaded rod is tightened hydraulically within the threaded through-hole for biasing the retaining platform against a pair of coil windings.